This invention relates to a method for recognizing a pellet pattern in the manufacture of a semiconductor device, and, in particular, a pellet pattern recognition method applied to a die-bonding operation effected after a good pellet is sequentially picked up from among pellets divided, as well as to a test operation using a prober.
Generally, during the manufacture of a semiconductor device, a die bonding step is carried out by placing a number of pellets (dies) having semiconductor elements on an XY stage of a die bonder and bonding a good pellet picked up from among the pellets to a proper position of a lead frame. The pellets on the XY stage are arranged in a matrix array with some distance left in the lateral direction and a direction perpendicular thereto, as set out below. A wafer on which semiconductor elements have been formed is bonded to a bonding sheet and then cut along a dicing line into a number of rectangular pellets. The bonding sheet is stretched in the lateral direction and a direction perpendicular thereto with some distance left between the dies and fixed on the surface of the XY stage. The shape identification is effected with respect to each pellet on the surface of the XY stage. Where the pellet is judged as being good, the position detection and pick-up of it are carried out. Where, on the other hand, the pellet is judged as being bad, it is not picked up and the XY stage is then shifted to pattern-recognize another pellet in a sequential fashion. Since all the pellets are sequentially pattern-recognized one by one, the efficiency of the die bonding operation is lowered dependent upon the number of bad pellets. The speed of the bonding operation varies due to a variation in the number of bad pellets, thus obtaining no high quality of bonding. Furthermore, the array of the pellets is disturbed and during the sequential pick-up of the pellets the pellet on one row may be displaced on another row with the result that more good pellets are left behind. In order to shift the XY stage to another pellet row subsequent to the termination of the pattern recognition for one row, a means such as an edge sensor is required to detect the outer edge of the wafer. A greater demand is made for a pellet pattern recognition method in which only good pellets can be efficiently and sequentially picked up one by one from among a number of good and bad pellets whose array is somewhat disturbed. Since the conventional method cannot perform an effective pick-up operation, there exists a problem of a lowering in the operational efficiency and in the quality of products. Furthermore, more good pellets are left behind. A solution to such problems is attempted to permit the complete automation of the manufacturing step of a semiconductor device.